1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
Note that in this specification, a semiconductor device generally means a device which can function by utilizing semiconductor characteristics. An electrooptic device, a display device (including a light-emitting display device), a semiconductor circuit, and an electronic device are all semiconductor devices.
2. Description of the Related Art
A technique in which a transistor is formed using a semiconductor thin film has attracted attention. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (also simply referred to as a display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a technique is disclosed by which a transistor is manufactured using zinc oxide or an In—Ga—Zn-based oxide as an oxide semiconductor (see Patent Documents 1 and 2).
In recent years, demand for an integrated circuit in which transistors and the like are integrated with high density has risen with reductions in the size and weight of an electronic device.